Methods and apparatus to generate an acoustic emission spectrum using chirp demodulation

ABSTRACT

Methods, apparatus, and articles of manufacture are disclosed. An example apparatus includes a pre-amplifier to condition an acoustic emission signal based on an acoustic emission source, a demodulator to generate demodulated acoustic emission data based on combining the acoustic emission signal with a chirp signal, and a transmitter to transmit the demodulated acoustic emission data to a data acquisition system.

FIELD OF THE DISCLOSURE

This disclosure relates generally to acoustic emission apparatus andmethods, and, more particularly, to methods and apparatus to generate anacoustic emission spectrum using chirp demodulation.

BACKGROUND

Acoustic emission sensors generate acoustic emission signals (e.g., anelectrical voltage signal) in response to acoustic emissions (e.g.,transient elastic waves) sensed, measured, and/or detected via a sensingelement (e.g., one or more piezoelectric crystals) of the acousticemission sensor. Sources of acoustic emissions may include the formationand/or propagation of a material defect (e.g., a crack), slip and/ordislocation movements of a material, etc.

Conventional acoustic emission measurement and detection environmentsinclude an acoustic emission sensor, a preamplifier, a filter, anamplifier, an analog to digital converter, and a data processing device(e.g., a computer). In such conventional environments, the acousticemission signals are typically conditioned and/or modified via thepreamplifier, the filter, the amplifier, and the analog to digitalconverter, and then subsequently analyzed at the data processing deviceto detect and/or characterize acoustic emission events (e.g., formationand/or propagation of a material defect, determination of a leakagerate, etc.) associated with the acoustic emission signals.

SUMMARY

Methods and apparatus to generate an acoustic emission spectrum usingchirp demodulation are disclosed herein. In some disclosed examples, anapparatus includes a pre-amplifier to condition an acoustic emissionsignal based on an acoustic emission source, a demodulator to generatedemodulated acoustic emission data based on combining the acousticemission signal with a chirp signal, and a transmitter to transmit thedemodulated acoustic emission data to a data acquisition system.

In some disclosed examples, a method includes conditioning an acousticemission signal based on an acoustic emission source with apre-amplifier integrated into an acoustic emission sensor, generating achirp signal, combining the acoustic emission signal with the chirpsignal, generating demodulated acoustic emission data based on thecombined signal, and transmitting the demodulated acoustic emission datato a data acquisition system.

In some disclosed examples, a non-transitory computer readable storagemedium comprising instructions is disclosed. In some disclosed examples,the instructions, when executed, cause a machine to at least conditionan acoustic emission signal based on an acoustic emission source with apre-amplifier integrated into an acoustic emission sensor, generate achirp signal, combine the acoustic emission signal with the chirpsignal, generate demodulated acoustic emission data based on thecombined signal, and transmit the demodulated acoustic emission data toa data acquisition system.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an example acoustic emissiondemodulator apparatus integrated into an example acoustic emissionpre-amplifier of an example acoustic emission sensor in accordance withthe teachings of this disclosure.

FIG. 2 is a schematic illustration of the example acoustic emissiondemodulator apparatus of FIG. 1 integrated into another example acousticemission sensor that includes another example acoustic emissionpre-amplifier in accordance with the teachings of this disclosure.

FIG. 3 is a schematic illustration of the example acoustic emissiondemodulator apparatus of FIGS. 1-2 integrated into yet another exampleacoustic emission pre-amplifier in accordance with the teachings of thisdisclosure.

FIG. 4 is a block diagram of an example implementation of the exampleacoustic emission demodulator apparatus of FIGS. 1-3, and the exampleacoustic emission sensor and the example acoustic emission pre-amplifierof FIG. 1.

FIG. 5 is a block diagram of an example implementation of the exampleacoustic emission demodulator apparatus of FIGS. 1-3, and the exampleacoustic emission sensor and the example acoustic emission pre-amplifierof FIG. 2.

FIG. 6 is a block diagram of an example implementation of the exampleacoustic emission demodulator apparatus of FIGS. 1-3, and the exampleacoustic emission sensor and the example acoustic emission pre-amplifierof FIG. 3.

FIGS. 7-9 are flowcharts representative of example methods that may beperformed using the example acoustic emission demodulator apparatusand/or the example acoustic emission sensor and/or the example acousticemission pre-amplifier of FIGS. 1-6 to generate an acoustic emissionspectrum using chirp demodulation.

FIG. 10A is an example graph depicting an example acoustic emissionsignal.

FIG. 10B is an example graph depicting an example mixed acousticemission signal.

FIG. 10C is an example graph depicting an example filtered mixedacoustic emission signal.

FIG. 10D is an example graph depicting example demodulated acousticemission data.

FIG. 11 is a block diagram of an example processor platform structuredto execute machine readable instructions to implement the methods ofFIGS. 7-9 and/or the example acoustic emission demodulator apparatus ofFIGS. 1-6, and/or the acoustic emission sensor and/or the acousticemission pre-amplifier of FIGS. 1 and 4.

FIG. 12 is a block diagram of another example processor platformstructured to execute machine readable instructions to implement themethods of FIGS. 7-9 and/or the example acoustic emission demodulatorapparatus of FIGS. 1-6, and/or the acoustic emission sensor and/or theacoustic emission pre-amplifier of FIGS. 2 and 5.

FIG. 13 is a block diagram of yet another example processor platformstructured to execute machine readable instructions to implement themethods of FIGS. 7-9 and/or the example acoustic emission demodulatorapparatus of FIGS. 1-6 and/or the acoustic emission pre-amplifier ofFIGS. 3 and 6.

The figures are not to scale. Wherever possible, the same referencenumbers will be used throughout the drawing(s) and accompanying writtendescription to refer to the same or like parts. As used herein, theterms “coupled” and “operatively coupled” are defined as connecteddirectly or indirectly (e.g., through one or more intervening structuresand/or layers).

DETAILED DESCRIPTION

Conventional acoustic emission measurement and detection environmentsinclude an acoustic emission sensor, a preamplifier, a filter, anamplifier, an analog to digital converter, and a data processing device(e.g., a computer). In such conventional environments, the acousticemission signals are typically conditioned and/or modified via thepreamplifier, the filter, the amplifier, and the analog to digitalconverter, and then subsequently analyzed at the data processing deviceto detect and/or characterize acoustic emission events (e.g., formationand/or propagation of a material defect, determination of a leakagerate, etc.) associated with the acoustic emission signals.

In some known acoustic emission measurement and detection environments,signal conditioning circuitry including the preamplifier, the filter,and the amplifier is included within a data acquisition device that alsoincludes the analog to digital converter. In other known acousticemission measurement and detection environments, the preamplifier andthe filter of the signal conditioning circuitry are integrated withinthe acoustic emission sensor, rather than being integrated within thedata acquisition device. In still other known acoustic emissionmeasurement and detection environments, the preamplifier and the filterof the signal conditioning circuitry are integrated within an externalpreamplifier device operatively located and/or positioned between theacoustic emission sensor and the data acquisition device, rather thanbeing integrated within the data acquisition device.

The above-described conventional acoustic emission measurement anddetection environments require high speed sampling (e.g., via the dataacquisition device) and extensive post-processing (e.g., via the dataprocessing device) to produce useful information regarding the integrityand/or health of the material(s) (e.g., process equipment) beingmonitored and/or evaluated. Examples of such useful information mayinclude determinations and/or estimations of leakage rate, flow rate,flow capacity, flow area, flow velocity, mass accumulation, and/orvolume accumulation associated with a process occurring within processequipment being monitored by the acoustic emission sensor, and mayfurther include determinations and/or estimations of valve health, valvewear, seal health, seal wear, and/or fugitive emissions associated withthe monitored process equipment.

The above-described conventional acoustic emission measurement anddetection environments fail to produce process information (e.g.,leakage rate data, flow rate data, valve health data, valve wear data,etc.) in real time without the use of external data acquisition devicesand/or computationally intensive post-processing systems. Moreover, theaforementioned high-speed sampling and extensive post-processingrequirements of such conventional acoustic emission measurement anddetections systems necessitate the implementation of high-end dataacquisition and data processing equipment, which increases thecomplexity and the cost of the acoustic emission measurement anddetection system. The implementation of such high-end equipment becomestechnologically challenging in low power and/or hazardous environments.

Unlike the above-described conventional acoustic emission measurementand detection environments, the example acoustic emission demodulatorapparatus and methods disclosed herein provide demodulation, filtering,and conversion of acoustic emission signals into values representing anamplitude or an energy present within a desired bandwidth. By usingdemodulation techniques, such as chirp demodulation, in a signalconditioning chain of acoustic emission signals, a frequency content ofa continuous acoustic emission source can be resolved without a need todigitally sample at high rates.

Chirp demodulation methods include generating chirp signals (e.g.,chirps), sweep signals, time-varying electrical signals, etc. In someexamples, a chirp signal is generated by a chirp function that sweeps aspecified frequency interval in a certain time interval. For example, achirp signal may include an electrical signal which increases (e.g., anup-chirp) or decreases (e.g., a down-chirp) in frequency with respect totime. For example, the frequency of the electrical signal may increaseor decrease linearly, exponentially, logarithmically, quadratically,etc., with respect to time. For example, in a linear chip, theinstantaneous frequency f(t) varies exactly linearly with time asdescribed below in Equation (1):f(t)=f ₀ +kt   Equation (1)In the illustrated example of Equation (1) above, t represents a pointin time, f₀ represents the start frequency (e.g., at time t=0), and krepresents the rate of frequency change, where k is described below inEquation (2):

$\begin{matrix}{k = \frac{f_{1} - f_{0}}{T}} & {{Equation}\mspace{14mu}(2)}\end{matrix}$In the illustrated example of Equation (2) above, f₁ represents the endfrequency and f₀ represents the start frequency. In the illustratedexample of Equation (2) above, T represents a sweep time or an amount oftime to sweep from f₀ to f₁.

In some examples, the chip signal (e.g., the sweeping electrical signal,the time-varying electrical signal, etc.) varies between a low point anda high point in a chirp bandwidth (e.g., an acoustic emission signalbandwidth, a frequency bandwidth, a measurement bandwidth, etc.). Forexample, the low point may be at or below the lowest frequency ofinterest in the acoustic emission signal bandwidth. The high point maybe at or above the highest frequency of interest in the acousticemission signal bandwidth. For example, the chirp signal may sweep(e.g., iteratively sweep) from the low point to the high point in theacoustic emission signal bandwidth within T as described above inconnection with Equation (2). In some examples, the chirp signal iscompared to and/or combined or mixed with an electrical signal ofinterest (e.g., an amplified acoustic emission signal of interest) togenerate demodulated data. For example, the demodulated data may includetime-varying data corresponding to frequency information (e.g., anamplitude, an energy, a frequency, etc.) of the electrical signal ofinterest varying with respect to time (e.g., average signal level data,root mean square data, time-averaged data, etc.).

Example acoustic emission demodulator (AED) apparatus disclosed hereinuse a chirp generator to generate chirp signals based on a bandwidth(e.g., a frequency bandwidth) of interest. In some disclosed examples,the chirp generator includes analog circuitry such as avoltage-controlled oscillator, a Yttrium iron garnet (YIG) oscillator,etc., to generate chirp signals. In some disclosed examples, the chirpgenerator includes digital circuitry such as a digital signal processorand a digital to analog converter using a direct digital synthesizer togenerate chirp signals. In some disclosed examples, the chirp generatorgenerates the chirp signals to sweep (e.g., iteratively sweep) between alow point and a high point of the bandwidth of interest. For example,the chirp generator may generate a chirp signal that iteratively sweepsfrom 15 kilohertz (kHz) to 1.1 megahertz (MHz) within 1 second based ona bandwidth of interest of 20 kHz to 1.0 MHz. Alternatively, any othersweep range, time period, and/or bandwidth of interest may be used.

In some disclosed examples, the AED apparatus combines the chirp signalwith a transient signal such as an acoustic emission signal to generatemixed acoustic emission data. For example, the AED apparatus may combinethe chirp signal with the acoustic emission signal by multiplying thesignals together and evaluating the resulting signal based on afractional set of frequency points (e.g., evaluating a subset of theresulting spectrum). When combining the chirp signal with the acousticemission signal, the amplitude or the intensity of the mixed acousticemission signal varies in line with the acoustic emission signal. Insome disclosed examples, the AED apparatus generates demodulatedacoustic emission data by extracting demodulated signal data tocharacterize or represent an acoustic emission source for a measurementtime period. For example, the demodulated signal data may includetime-averaged data such as average signal level (ASL) data, root meansquare data, etc. In another example, the demodulated signal data mayinclude spectral data (e.g., acoustic emission spectral data such as anamplitude, an energy, a frequency, etc., and/or a combination thereofvarying with respect to the chirp signal). For example, the AEDapparatus may extract an amplitude from the mixed acoustic emissiondata, map the extracted amplitude to a corresponding time value, and mapthe time value to a corresponding frequency. In such an example, theextracted signal data may include a mixture of time and frequencyinformation.

In some disclosed examples, the AED apparatus directs the acousticemission sensor, the pre-amplifier, etc., to display information (e.g.,the time-averaged data, the spectral data, etc.) on a presentationdevice on the acoustic emission sensor, the pre-amplifier, etc. In somedisclosed examples, the AED apparatus transmits the information to anexternal data acquisition system via an analog communication protocol ora digital communication protocol. In such disclosed examples, the AEDapparatus transmits the information at a substantially lower ratecompared to a rate necessary to record the transient signal whilerequiring less data points to adequately represent the spectrum of thetransient signal.

FIG. 1 is a schematic illustration of an example acoustic emissiondemodulator (AED) 100 integrated into an example acoustic emissionsensor 102 in accordance with the teachings of this disclosure. In theillustrated example, the acoustic emission sensor 102 is coupled to afluid flow control assembly 104 operating in a process controlenvironment 106. The acoustic emission sensor 102 of the illustratedexample is a transducer that generates acoustic emission signals 108(e.g., an electrical voltage signal) in response to acoustic emissions(e.g., transient elastic waves) sensed, measured, and/or detected via asensing element 110 (e.g., one or more piezoelectric crystals) of theacoustic emission sensor 102. For example, the acoustic emission signals108 may be electrical voltage signals generated by the sensing element110 which represent an acoustic emission spectrum of one or moreacoustic emission sources. In such an example, the acoustic emissionsensor 102 may process the acoustic emission signals 108 to generatedata (e.g., the time-averaged signal of one or more bandwidths and/or acomplete spectrum of the acoustic emission signals 108 over a sampleperiod).

In the illustrated example, the acoustic emission sensor 102 includes apre-amplifier 112, which includes the AED 100. The pre-amplifier 112 ofthe illustrated example conditions the acoustic emission signal 108 byamplifying, boosting, strengthening, and/or filtering the acousticemission signal 108 to generate pre-amplified acoustic emission data. Insome examples, the pre-amplifier 112 amplifies, boosts, and/orstrengthens the acoustic emission signal 108 prior to filtering theacoustic emission signal 108. In other examples, the pre-amplifier 112amplifies, boosts, and/or strengthens the acoustic emission signal 108after filtering the acoustic emission signal 108. For example, thepre-amplifier 112 may filter the acoustic emission signal 108 via one ormore filters such as a band-pass filter, a low-pass filter, a high-passfilter, etc., and/or a combination thereof. In another example, thepre-amplifier 112 may inherently filter the acoustic emission signal 108via interacting with the voltage signal produced by the sensing element110 due to an impedance characteristic of one or more amplifiers (e.g.,an operational amplifier, a differential amplifier, etc.) included inthe pre-amplifier 112. In another example, the pre-amplifier 112 mayamplify, boost, and/or strengthen the acoustic emission signal 108 usinga configurable gain based on one or more components such as adifferential amplifier, an operational amplifier, etc., and/or acombination thereof. As used herein, the terms “pre-amplified acousticemission data” and “pre-amplified acoustic emission signal” are usedinterchangeably and refer to the acoustic emission signal 108 that hasbeen amplified and/or filtered by the pre-amplifier 112.

In the illustrated example, the AED 100 includes a chirp generator togenerate a chirp signal (e.g., a time-varying electrical signal) at anincreasing or decreasing frequency. In the illustrated example, the AED100 combines the chirp signal with the acoustic emission signal 108 togenerate mixed acoustic emission data. As used herein, the terms “mixedacoustic emission data” and “mixed acoustic emission signal” are usedinterchangeably and refer to the pre-amplified acoustic emission datathat has been processed by the AED 100. For example, mixed acousticemission data may include an electrical signal resulting from combiningthe acoustic emission signal 108 with an electrical signal generated bythe chirp generator.

In some examples, the AED 100 generates acoustic emission data tocharacterize or represent an acoustic emission source during ameasurement time period and within an AE signal bandwidth selection ofthe chirp generator (e.g., a chirp generator bandwidth). For example,the bandwidth selection may correspond to an AE signal bandwidth of 20kHz to 40 kHz. In another example, the bandwidth selection maycorrespond to a data extractor bandwidth of 45 kHz to 65 kHz. As usedherein, the terms “demodulated acoustic emission data,” “demodulatedacoustic emission signal data,” and “demodulated signal data” are usedinterchangeably and refer to the data or information extracted fromand/or processed based on the mixed acoustic emission data. For example,the demodulated acoustic emission data may include spectral information(e.g., an amplitude, an energy, frequency information, etc., and/or acombination thereof). In another example, the demodulated acousticemission data may include time-averaged information (e.g., ASL data, RMSdata, etc.), etc. As used herein, the term “frequency information”refers to processed data such as an amplitude value, a frequency value,etc., extracted from the mixed acoustic emission data by using one ormore configurations, settings, etc., of the one or more filters and/orthe one or more oscillators included in the AED 100 of FIG. 1.

In some examples, the demodulated acoustic emission data includes acombination of spectral information and time-averaged information. Forexample, the demodulated acoustic emission data may include informationfrom the time domain and/or the frequency domain. For example, the AED100 may extract spectral information, time-averaged information, etc.,and/or a combination thereof from the mixed acoustic emission data every10 milliseconds, 100 milliseconds, etc. In such an example, thedemodulated acoustic emission data represents data and informationcorresponding to the acoustic emission signal 108 based on an acousticemission source (e.g., a continuous acoustic emission source) of thefluid flow control assembly 104. For example, the demodulated acousticemission data may include a spectrum representative of the acousticemission source.

In the illustrated example, the AED 100 generates demodulated acousticemission data to detect the formation and/or propagation of one or moredefect(s) (e.g., a crack in a valve 120) and/or one or more event(s)associated with the defect(s) (e.g., a leakage rate associated with theformation and/or propagation of the defect) in the fluid flow controlassembly 104 of FIG. 1. The fluid flow control assembly 104 of theillustrated example is a pneumatically actuated valve assembly. In theillustrated example, the fluid flow control assembly 104 is controlledby a field device 114 such as an electronic valve controller housed inan enclosure 116. The enclosure 116 is coupled to the fluid flow controlassembly 104, which includes at least an actuator 118 and the valve 120(e.g., a butterfly valve, a globe valve, etc.). The actuator 118 of theillustrated example is activated via changes in pneumatic pressure froma pneumatic tube connection 122. However, other valve assemblies mayadditionally or alternatively be used, such as an electrically actuatedvalve assembly, a hydraulically actuated valve assembly, etc.

In the illustrated example, the acoustic emission sensor 102 iscommunicatively coupled to an example external data acquisition system124. The example acoustic emission sensor 102 of the illustrated exampleis communicatively coupled to the data acquisition system 124 via acable 126 that includes one or more wires. Additionally oralternatively, the example acoustic emission sensor 102 may be connectedto the example data acquisition system 124 via a wireless connection.For example, the acoustic emission sensor 102 may communicate with thedata acquisition system 124 via a Bluetooth® connection, a Wi-Fi Direct®network, etc.

In some examples, the data acquisition system 124 is a process controlsystem or a part of a process control system (e.g., the data acquisitionsystem 124 is communicatively coupled to a process control system) thatincludes a controller for data acquisition and/or process control. Inthe illustrated example, the acoustic emission sensor 102 transmitsinformation (e.g., the acoustic emission signal 108, the demodulatedacoustic emission data, etc.) to the data acquisition system 124. Forexample, the acoustic emission sensor 102 may transmit spectralinformation, time-averaged information, etc., and/or a combinationthereof based on the acoustic emission signal 108 to the dataacquisition system 124. In the illustrated example, the data acquisitionsystem 124 transmits information to the acoustic emission sensor 102.For example, the data acquisition system 124 may transmit configurationselection data such as a sweep time for a chirp generator included inthe AED 100, a gain of the pre-amplifier 112, etc.

FIG. 2 is a schematic illustration of the example AED 100 of FIG. 1integrated into another example acoustic emission sensor 200 thatincludes another example acoustic emission pre-amplifier 202 inaccordance with the teachings of this disclosure. The acoustic emissionsensor 200 of the illustrated example is a transducer that generates theacoustic emission signals 108 of FIG. 1 based on the sensing element 110of FIG. 1 as described above in connection with the acoustic emissionsensor 102 of FIG. 1. In the illustrated example, the pre-amplifier 202conditions the acoustic emission signal 108 of FIG. 1 by amplifying,boosting, strengthening, and/or filtering the acoustic emission signal108 as described above in connection with the pre-amplifier 112 ofFIG. 1. In some examples, the pre-amplifier 202 amplifies, boosts,and/or strengthens the acoustic emission signal 108 prior to filteringthe acoustic emission signal 108. In other examples, the pre-amplifier202 amplifies, boosts, and/or strengthens the acoustic emission signal108 after filtering the acoustic emission signal 108. For example, thepre-amplifier 202 may filter the acoustic emission signal 108 and/or usea configurable gain as described above in connection with thepre-amplifier 112 of FIG. 1.

In the illustrated example, the AED 100 obtains pre-amplified acousticemission data from the pre-amplifier 202. For example, the AED 100 mayuse a chirp generator to generate a chirp signal. In such an example,the AED 100 may combine the chirp signal with the pre-amplified acousticemission data to generate mixed acoustic emission data. In theillustrated example, the AED 100 extracts demodulated acoustic emissiondata from the mixed acoustic emission data representative of an acousticemission source during a measurement time period and within an AE signalbandwidth selection of the chirp generator, and transmits thedemodulated acoustic emission data to the data acquisition system 124 ofFIG. 1.

In the illustrated example, the pre-amplifier 202 is separate from theAED 100. For example, the AED 100 and the pre-amplifier 202 may beseparate hardware, software, firmware and/or any combination ofhardware, software and/or firmware. In such an example, the AED 100 maybe implemented by first hardware that includes one or more analog ordigital circuit(s), logic circuits, programmable processor(s),application specific integrated circuit(s) (ASIC(s)), programmable logicdevice(s) (PLD(s)) and/or field programmable logic device(s) (FPLD(s))while the pre-amplifier 202 may be implemented by second hardware thatincludes one or more analog or digital circuit(s), logic circuits,programmable processor(s), application specific integrated circuit(s)(ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)). In another or in the sameexample, the AED 100 and the pre-amplifier 202 may be executed byseparate software components such as different software algorithms,computer readable instructions, software applications, software modules,or software programs, etc.

FIG. 3 is a schematic illustration of the example AED 100 of FIGS. 1-2integrated into yet another example acoustic emission pre-amplifier 300,which is external to or separate from yet another example acousticemission sensor 302 in accordance with the teachings of this disclosure.In the illustrated example, the pre-amplifier 300 is communicativelycoupled to the acoustic emission sensor 302. The acoustic emissionsensor 302 of the illustrated example is a transducer that generates theacoustic emission signals 108 of FIGS. 1-2 based on the sensing element110 of FIGS. 1-2 as described above in connection with the acousticemission sensor 102 of FIG. 1 and/or the acoustic emission sensor 200 ofFIG. 2.

In the illustrated example, the pre-amplifier 300 conditions theacoustic emission signal 108 of FIGS. 1-2 by amplifying, boosting,strengthening, and/or filtering the acoustic emission signal 108 asdescribed above in connection with the pre-amplifier 112 of FIG. 1and/or the pre-amplifier 202 of FIG. 2. In some examples, thepre-amplifier 300 amplifies, boosts, and/or strengthens the acousticemission signal 108 prior to filtering the acoustic emission signal 108.In other examples, the pre-amplifier 300 amplifies, boosts, and/orstrengthens the acoustic emission signal 108 after filtering theacoustic emission signal 108. For example, the pre-amplifier 300 mayfilter the acoustic emission signal 108 and/or use a configurable gainas described above in connection with the pre-amplifier 112 of FIG. 1and/or the pre-amplifier 202 of FIG. 2.

In the illustrated example of FIG. 3, the AED 100 obtains pre-amplifiedacoustic emission data from the pre-amplifier 300 based on the acousticemission signal 108. For example, the AED 100 may use a chirp generatorto generate a chirp signal. In such an example, the AED 100 may combinethe chirp signal with the pre-amplified acoustic emission data based onthe acoustic emission signal 108 to generate mixed acoustic emissiondata. In the illustrated example, the AED 100 extracts demodulatedacoustic emission data from the mixed acoustic emission datarepresentative of an acoustic emission source during a measurement timeperiod and within an AE signal bandwidth selection of the chirpgenerator, and transmits the demodulated acoustic emission data to thedata acquisition system 124 of FIGS. 1-2 via a cable 304 that includesone or more wires. The example pre-amplifier 300 may additionally oralternatively be connected to the data acquisition system 124 via awireless connection. For example, the pre-amplifier 300 of FIG. 3 maycommunicate with the data acquisition system 124 via a Bluetooth®connection, a Wi-Fi Direct® network, etc.

FIG. 4 is a block diagram of an example implementation of the exampleAED 100 of FIGS. 1-3, and the example acoustic emission sensor 102 andthe example acoustic emission pre-amplifier 112 of FIG. 1 in accordancewith the teachings of this disclosure. In the illustrated example, theacoustic emission sensor 102 includes the pre-amplifier 112 to amplify,boost, strengthen, and/or filter the acoustic emission signal 108 ofFIGS. 1-3. In the illustrated example, the pre-amplifier 112 includes anexample amplifier 400 (e.g., an input amplifier) and an example filter405. In the illustrated example, the acoustic emission signal 108 isbased on the sensing element 110 of FIGS. 1-3 sensing, measuring, and/ordetecting an acoustic emission 408. For example, the acoustic emission408 may be a formation and/or a propagation of a material defectassociated with the fluid flow control assembly 104 of FIGS. 1-3.

In the illustrated example of FIG. 4, the pre-amplifier 112 includes theinput amplifier 400 to increase a characteristic, a parameter, etc., ofthe acoustic emission signal 108 such as a power, a voltage, etc. Forexample, the input amplifier 400 may be an impedance converter such as anegative impedance converter, a positive impedance converter, etc. Insome examples, the input amplifier 400 includes one or more amplifierssuch as a differential amplifier, an operational amplifier, etc., and/ora combination thereof. For example, the input amplifier 400 may increasea voltage of the acoustic emission signal 108 from a first voltage to asecond voltage based on a gain value, where the gain value is based onan electrical circuit included in the input amplifier 400. In such anexample, the electrical circuit may include an operational amplifier incircuit with one or more passive electrical components such as acapacitor, a resistor, etc., and/or a combination thereof. In someexamples, the gain value is variable. In other examples, the gain valueis fixed.

In the illustrated example, the input amplifier 400 amplifies, boosts,and/or strengthens an acoustic emission signal 108 to an acceptablelevel to be processed by one or more other components in the acousticemission sensor 102 such as the AED 100. For example, the AED 100 mayrequire an input voltage level of 1 volt for the acoustic emissionsignal 108. In such an example, the input amplifier 400 may increase avoltage of the acoustic emission signal 108 from 100 millivolts to 1volt based on a gain of 20 decibels (e.g., 20 decibels=20×log(1 volt÷100millivolts)).

In the illustrated example of FIG. 4, the pre-amplifier 112 includes thefilter 405 to remove acoustic emission frequency information from theacoustic emission signal 108 obtained from the input amplifier 400. Insome examples, the filter 405 includes one or more filters such as aband-pass filter, a low-pass filter, a high-pass filter, etc., and/or acombination thereof. The filter 405 of the illustrated example may beimplemented as any type of filter including, for example, active,passive, superheterodyne, envelope detection, capacitor switching, fieldprogrammable gate array, finite impulse response, infinite impulseresponse, etc. For example, the filter 405 may include a band-passfilter to remove acoustic emission frequency information outside of afrequency range of 20 kHz to 40 kHz. Alternatively, the filter 405 maybe incorporated into the input amplifier 400. For example, the inputamplifier 400 and the filter 405 may output pre-amplified acousticemission data.

In the illustrated example of FIG. 4, the acoustic emission sensor 102includes the AED 100 to generate acoustic emission spectral data basedon pre-amplified acoustic emission data. Alternatively, the example AED100 may process the example acoustic emission signal 108 prior to theexample input amplifier 400 and/or the example filter 405 conditioningthe acoustic emission signal 108. In the illustrated example, the AED100 includes a chirp generator 410 to create chirp signals that includeelectrical signals which vary with respect to time by increasing ordecreasing in frequency.

In some examples, the chirp generator 410 includes one or moreoscillators to generate the chirp signals within a specified frequencyrange based on information from the configuration selector 440. Forexample, the chirp generator 410 may generate the chirp signals based ona frequency range (e.g., a frequency range based on a start frequencyvalue, an end frequency value, etc.) and/or a sweep time of interest. Insuch an example, the chirp generator 410 may obtain the frequency rangeand/or the sweep time of interest from the configuration selector 440.For example, the chirp generator 410 may obtain a start frequency valueof 25 kHz, an end frequency value of 1.1 MHz, and a sweep time of 100milliseconds from the configuration selector 440. In some examples, thechirp generator 410 determines whether to generate chirp signals usinganother frequency range and/or another sweep time of interest. Forexample, the chirp generator 410 may obtain a start frequency value of50 kHz, an end frequency value of 450 kHz, and a sweep time of 150milliseconds from the configuration selector 440.

In some examples, the chirp generator 410 generates chirp signals usingone or more oscillators. For example, the chirp generator 410 mayinclude one or more voltage-controlled oscillators, Yttrium iron garnet(YIG) oscillators, etc., and/or a combination thereof to generate chirpsignals. Additionally or alternatively, the example chirp generator 410may generate chirp signals using one or more digital circuits thatinclude one or more digital signal processors, one or more digital toanalog converters, and/or one or more direct digital synthesizers, etc.,and/or a combination thereof.

In the illustrated example of FIG. 4, the AED 100 includes a mixer 415to combine a chirp signal with the pre-amplified acoustic emissionsignal to generate a mixed acoustic emission signal. In the illustratedexample, the mixer 415 combines the output (e.g., the electrical output,the software output, etc.) of the filter 405 with the output of thechirp generator 410 to produce a frequency-shifted version of thepre-amplified acoustic emission signal overlapping an intermediatefrequency band. For example, the mixer 415 may shift one or morefrequencies of the pre-amplified acoustic emission signal towards anintermediate frequency which may be a lower or a higher frequency thanthat of the frequency of the pre-amplified acoustic emission signal.

For example, the mixer 415 may shift a first measurement centerfrequency in a measurement bandwidth of 50-450 kHz to an intermediatefrequency such as an intermediate center frequency of 10 MHz and anintermediate frequency bandwidth of 50 kHz. In another example, themixer 415 may multiply the output of the filter 405 with the output ofthe chirp generator 410 to generate information in the frequency domain,the time-domain, etc., and/or a combination thereof. Additionally oralternatively, the example mixer 415 may combine the outputs by anyother mathematical operation, process, etc., including a convolutionoperation, a Fourier transform operation, etc.

In the illustrated example of FIG. 4, the AED 100 includes a dataextractor 420 to generate example demodulated signal data 425 (e.g., ademodulated acoustic emission signal) from the mixed acoustic emissiondata (e.g., a mixed acoustic emission signal) based on the acousticemission signal 108. In some examples, the data extractor 420 filtersand/or selects frequencies of interest (e.g., a filter bandwidth, afrequency bandwidth, etc.) around the intermediate center frequency. Forexample, the data extractor 420 may filter (e.g., filter using aband-pass filter, a low-pass filter, etc., and/or a combination thereof)a mixed acoustic emission signal to remove frequency information thatdoes not fall within a bandwidth of interest to generate a filteredmixed acoustic emission signal. For example, the data extractor 420 mayuse a band-pass filter to remove all but one of the sidebands (e.g., alower sideband, an upper sideband, etc.) of the mixed acoustic emissionsignal to generate a single sideband acoustic emission signal. Inanother example, the data extractor 420 may use a low-pass filter and anenvelope detector to extract low frequency information of interest togenerate a double sideband acoustic emission signal, a full-bandacoustic emission signal, etc.

In some examples, the data extractor 420 generates demodulated signaldata 425 based on generating one or more single sideband acousticemission signals. For example, the data extractor 420 may samplespectral information of a single sideband acoustic emission signal at ameasurement center frequency based on an instantaneous frequency valueof a chirp signal. The example data extractor 420 may generate alow-resolution and high-bandwidth spectrum by sampling one or moremeasurements of the filtered mixed acoustic emission data in sync withthe chirp signal. For example, the data extractor 420 may (1) take ameasurement every time a single sideband acoustic emission signal isgenerated based on the chirp signal increasing or decreasing infrequency, (2) build a spectrum based on the measurements, and (3)generate the demodulated signal data 425 based on the spectrum.

In some examples, the data extractor 420 includes an amplifier (e.g., alog amplifier) to convert an input voltage of the filtered mixedacoustic emission signal to an output voltage proportional to alogarithm (e.g., a natural logarithm, a base 10 logarithm, etc.) of theinput voltage. In such examples, the data extractor 420 averages theoutput voltages over a time period to generate demodulated signal data.In some examples, the demodulated signal data 425 includes root meansquare (RMS) data associated with the filtered mixed acoustic emissionsignal. For example, the data extractor 420 may extract and/or calculateRMS data from the filtered mixed acoustic emission data by squaring thevalues of the filtered mixed acoustic emission data (e.g., squaring thefunction that defines the waveform of the mixed acoustic emission data),by taking the average of the squared values (e.g., the average of thesquared function), and by taking the square root of the average values(e.g., the square root of the average function).

In some examples, the demodulated signal data 425 includes analog dataand/or digital data. For example, the demodulated signal data 425 may bean analog signal such as an electrical voltage. In another example, thedemodulated signal data 425 may be a digital signal corresponding to abinary value, a hexadecimal value, etc. In other examples, thedemodulated signal data 425 includes ASL data associated with thefiltered mixed acoustic emission data. For example, the data extractor420 may extract and/or calculate ASL data from the filtered mixedacoustic emission data by taking the average signal values (e.g., theaverage of the function that defines the waveform of the filtered mixedacoustic emission data) as a function of time.

In some examples, the demodulated signal data 425 includes spectralinformation associated with the filtered mixed acoustic emission data.For example, the data extractor 420 may extract spectral content dataassociated with the filtered mixed acoustic emission data, and/ortransient data associated with the filtered mixed acoustic emissiondata. The demodulated signal data 425 of FIG. 4 may include suchspectral content data and/or transient data. In some examples, the dataextractor 420 builds a spectrum based on the filtered mixed acousticemission data, where the demodulated signal data 425 includes thespectrum. For example, the data extractor 420 may sweep the measurementbandwidth, select a sample (e.g., spectral information) within eachbandwidth region, and build a low-resolution and high-bandwidth spectrumbased on the samples. For example, the data extractor 420 may sample thespectral information included in the filtered mixed acoustic emissiondata in sync with the chirp signal generated by the chirp generator 410.For example, the data extractor 420 may sample the spectral informationwith every increase or decrease of the chirp signal.

In some examples, the data extractor 420 generates an alert wheninformation included in the demodulated signal data 425 satisfies athreshold. For example, the data extractor 420 may compare a voltageamplitude included in the demodulated signal data 425 to a voltageamplitude threshold value (e.g., 0.1 Volts, 0.5 Volts, 1.2 Volts, etc.).In such an example, the data extractor 420 may generate an alert whenthe voltage amplitude is greater than the voltage amplitude thresholdvalue (e.g., the voltage amplitude of 1.5 Volts is greater than thevoltage amplitude threshold value of 1.2 Volts). Additionally oralternatively, the data extractor 420 may generate an alert when anenergy value, a frequency value, etc., included in the demodulatedsignal data 425 satisfies an energy value threshold, a frequency valuethreshold, etc.

In the illustrated example of FIG. 4, the pre-amplifier 112 includes atransmitter 430 to transmit information (e.g., the acoustic emissionsignal 108, the demodulated signal data 425, an alert, etc.) to the dataacquisition system 124 of FIGS. 1-3. Alternatively, the exampletransmitter 430 may be integrated into the example AED 100. Thetransmitter 430 of the illustrated example may be implemented by anytype of interface standard, such as an Ethernet interface, a universalserial bus (USB), and/or a PCI express interface. The transmitter 430 ofthe illustrated example may further include a modem and/or a networkinterface card to facilitate exchange of data with the data acquisitionsystem 124 via a network 435. In some examples, the network 435 overwhich the transmitter 430 exchange(s) data with the data acquisitionsystem 124 may be facilitated via 4-20 milliamp wiring and/or via one ormore communication protocol(s) including, for example, HighwayAddressable Remote Transducer (HART), Foundation Fieldbus, TransmissionControl Protocol/Internet Protocol (TCP/IP), Profinet, Modbus and/orEthernet.

In the illustrated example of FIG. 4, the network 435 is a bus and/or acomputer network. For example, the network 435 may be a process controlnetwork, a direct wired or a direct wireless connection to the dataacquisition system 124, etc. In some examples, the network 435 is anetwork with the capability of being communicatively coupled to theInternet. However, the example network 435 may be implemented using anysuitable wired and/or wireless network(s) including, for example, one ormore data buses, one or more Local Area Networks (LANs), one or morewireless LANs, one or more cellular networks, one or more fiber opticnetworks, one or more satellite networks, one or more private networks,one or more public networks, etc. The example network 435 may enable theexample acoustic emission sensor 102 to be in communication with theexample data acquisition system 124. As used herein, the phrase “incommunication,” including variances thereof, encompasses directcommunication and/or indirect communication through one or moreintermediary components and does not require direct physical (e.g.,wired) communication and/or constant communication, but rather includesselective communication at periodic or aperiodic intervals, as well asone-time events.

In the illustrated example of FIG. 4, the pre-amplifier 112 includes aconfiguration selector 440 to configure, modify, and/or select aconfiguration or a parameter (e.g., a configuration parameter) of one ormore components in the acoustic emission sensor 102 based on exampleconfiguration selection data 445. For example, the configurationselector 440 may configure the input amplifier 400, the filter 405, thechirp generator 410, the transmitter 430, etc., based on obtaining theconfiguration selection data 445 from the data acquisition system 124and/or a database 450. For example, the configuration selector 440 mayobtain a start frequency value, a final or an end frequency value, asweep time value, etc., from the data acquisition system 124 andconfigure the chirp generator 410 with the obtained information. Forexample, the configuration selector 440 may modify the start frequencyvalue, the end frequency value, the sweep time value, etc., of the chirpgenerator 410. In some examples, the configuration selector 440 storesthe configuration selection data 445 in the database 450. In someexamples, the configuration selector 440 retrieves the configurationselection data 445 from the database 450.

In some examples, the configuration selector 440 obtains theconfiguration selection data 445 and compares information (e.g.,acoustic emission sensor component parameter values, process controlenvironment parameter values, etc.) included in the configurationselection data 445 to stored information in the database 450. Forexample, the configuration selector 440 may (1) obtain a first value fora sweep time from the data acquisition system 124, (2) compare the firstvalue to a second value for the sweep time stored in the database 450,and (3) replace the second value with the first value when theconfiguration selector 440 determines they are different. In response todetermining that the first and the second values are not different, theexample configuration selector 440 discards the first value and keepsthe second value stored in the database 450.

In the illustrated example of FIG. 4, the configuration selection data445 includes parameter information, parameter values, etc., that can beused to configure one or more components of the AED 100, thepre-amplifier 112, and/or more generally, the acoustic emission sensor102. In some examples, the configuration selection data 445 includes again parameter value, a direct current (DC) offset parameter value,etc., to configure or modify the input amplifier 400 of FIG. 4. In someexamples, the configuration selection data 445 includes a type of one ormore filters (e.g., a low-pass filter, a high-pass filter, a band-passfilter, a band-stop filter, etc.), a setting of the one or more filters(e.g., an input sensor signal range, a noise rejection level, etc.),etc., to configure the one or more filters included in the filter 405 ofFIG. 4.

In some examples, the configuration selection data 445 of FIG. 4includes a start frequency value, an end frequency value, a sweep timevalue, etc., to configure or modify the chirp generator 410 of FIG. 4.In some examples, the configuration selection data 445 includes processcontrol environment data such as a valve size, a valve type, etc., ofthe fluid flow control assembly 104 of FIGS. 1-4. For example, the dataextractor 420 may generate and/or process the demodulated signal data425 to correspond to the process control environment data. In someexamples, the configuration selection data 445 includes a parametercorresponding to a communication interface, a communication protocol,etc., to configure or modify the transmitter 430. For example, theconfiguration selection data 445 may include a communication parametersuch as an Internet Protocol (IP) address and a port number to configurethe transmitter 430 for Ethernet-based communication. In anotherexample, the configuration selection data 445 may include acommunication parameter such as an address, a manufacturer code, etc.,to configure the transmitter 430 for HART communication.

In some examples, the configuration selection data 445 includes acousticemission data analysis information such as alert threshold values, cycletimes for obtaining the acoustic emission signal 108 and/or generatingthe demodulated signal data 425, etc. For example, the configurationselection data 445 may include a threshold value to be used by the dataextractor 420 to generate an alert when information included in thedemodulated signal data 425 satisfies a threshold. For example, thetransmitter 430 may transmit an alert generated by the data extractor420 when a voltage amplitude, a frequency, etc., included in thedemodulated signal data 425 is greater than an amplitude thresholdvalue, a frequency threshold value, etc.

In the illustrated example of FIG. 4, the pre-amplifier 112 includes thedatabase 450 to record data (e.g., the configuration selection data445). In some examples, the database 450 records the acoustic emissionsignal 108, the demodulated signal data 425, etc. The example database450 may respond to queries for information related to data in thedatabase 450. For example, the database 450 may respond to queries foradditional data by providing the additional data (e.g., the one or moredata points), by providing an index associated with the additional datain the database 450, etc. The example database 450 may additionally oralternatively respond to queries when there is no additional data in thedatabase 450 by providing a null index, an end of database 450identifier, etc.

The example database 450 may be implemented by a volatile memory (e.g.,a Synchronous Dynamic Random Access Memory (SDRAM), Dynamic RandomAccess Memory (DRAM), RAMBUS Dynamic Random Access Memory (RDRAM), etc.)and/or a non-volatile memory (e.g., flash memory). The example database450 may additionally or alternatively be implemented by one or moredouble data rate (DDR) memories, such as DDR, DDR2, DDR3, DDR4, mobileDDR (mDDR), etc. The example database 450 may additionally oralternatively be implemented by one or more mass storage devices such ashard disk drive(s), compact disk drive(s) digital versatile diskdrive(s), solid-state drive(s), etc. While in the illustrated examplethe database 450 is illustrated as a single database, the database 450may be implemented by any number and/or type(s) of databases. Althoughthe example database 450 is depicted in FIG. 4 as being included in thepre-amplifier 112, alternatively the database 450 may be separate fromthe pre-amplifier 112.

In the illustrated example, the acoustic emission sensor 102 includes apresentation device 455 to present data in visual and/or audible form atthe acoustic emission sensor 102 of FIG. 4 including, for example, someor all of the demodulated signal data 425, some or all of theconfiguration selection data 445, a generated alert by the dataextractor 420, etc. For example, the presentation device 455 may beimplemented as one or more of a light emitting diode, a touchscreen,and/or a liquid crystal display for presenting visual information,and/or a speaker for presenting audible information. In some examples,the presentation of data via the presentation device 455 of the acousticemission sensor 102 is controlled and/or managed by the data extractor420.

While an example manner of implementing the example acoustic emissionsensor 102, the example pre-amplifier 112, and/or the example AED 100 ofFIG. 1 is illustrated in FIG. 4, one or more of the elements, processesand/or devices illustrated in FIG. 4 may be combined, divided,re-arranged, omitted, eliminated and/or implemented in any other way.Further, the example AED 100, the example pre-amplifier 112, the exampleinput amplifier 400, the example filter 405, the example chirp generator410, the example mixer 415, the example data extractor 420, the exampletransmitter 430, the example configuration selector 440, the exampledatabase 450, the example presentation device 455, and/or, moregenerally, the example acoustic emission sensor 102 of FIG. 4 may beimplemented by hardware, software, firmware and/or any combination ofhardware, software and/or firmware. Thus, for example, any of theexample AED 100, the example pre-amplifier 112, the example inputamplifier 400, the example filter 405, the example chirp generator 410,the example mixer 415, the example data extractor 420, the exampletransmitter 430, the example configuration selector 440, the exampledatabase 450, the example presentation device 455, and/or, moregenerally, the example acoustic emission sensor 102 could be implementedby one or more analog or digital circuit(s), logic circuits,programmable processor(s), application specific integrated circuit(s)(ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)). When reading any of theapparatus or system claims of this patent to cover a purely softwareand/or firmware implementation, at least one of the example AED 100, theexample pre-amplifier 112, the example input amplifier 400, the examplefilter 405, the example chirp generator 410, the example mixer 415, theexample data extractor 420, the example transmitter 430, the exampleconfiguration selector 440, the example database 450, and/or the examplepresentation device 455 is/are hereby expressly defined to include anon-transitory computer readable storage device or storage disk such asa memory, a digital versatile disk (DVD), a compact disk (CD), a Blu-raydisk, etc. including the software and/or firmware. Further still, theexample acoustic emission sensor 102 of FIG. 1 may include one or moreelements, processes and/or devices in addition to, or instead of, thoseillustrated in FIG. 4, and/or may include more than one of any or all ofthe illustrated elements, processes and devices.

FIG. 5 is a block diagram of an example implementation of the exampleAED 100 of FIGS. 1-4, and the example acoustic emission sensor 200 andthe example pre-amplifier 202 of FIG. 2 in accordance with the teachingsof this disclosure. In the illustrated example, the acoustic emissionsensor 200 includes the pre-amplifier 202 to amplify, boost, strengthen,and/or filter the acoustic emission signal 108 of FIGS. 1-4 based on thesensing element 110 of FIGS. 1-4 sensing, measuring, and/or detectingthe acoustic emission 408 of FIG. 4. In the illustrated example, thepre-amplifier 202 includes the example input amplifier 400 and theexample filter 405 to amplify, boost, strengthen, and/or filter theacoustic emission signal 108 as described above in connection with FIG.4.

In the illustrated example of FIG. 5, the AED 100 is separate from ornot integrated with the pre-amplifier 202. The AED 100 of theillustrated example uses the data extractor 420 to generate thedemodulated signal data 425 based on mixed acoustic emission dataobtained from the mixer 415. Alternatively, the example AED 100 mayprocess the example acoustic emission signal 108 prior to the examplepre-amplifier 202 conditioning the acoustic emission signal 108. In theillustrated example, the transmitter 430, the configuration selector440, the database 450, and the presentation device 455 are separate fromor not integrated with the pre-amplifier 202. Alternatively, the exampletransmitter 430, the example configuration selector 440, the exampledatabase 450, and/or the example presentation device 455 may beintegrated with the example AED 100, the example pre-amplifier 202, etc.The acoustic emission sensor 200 of the illustrated example transmitsinformation to the data acquisition system 124 via the transmitter 430.For example, the transmitter 430 may transmit the acoustic emissionsignal 108, the demodulated signal data 425, etc., to the dataacquisition system 124 via the network 435.

In connection with the illustrated example of FIG. 5, the structure,function, and/or operation of each of the AED 100, the input amplifier400, the filter 405, the chirp generator 410, the mixer 415, the dataextractor 420, the demodulated signal data 425, the transmitter 430, thenetwork 435, the configuration selector 440, the configuration selectiondata 445, the database 450, and the presentation device 455 is/are thesame as the corresponding structure, function, and/or operation of theAED 100, the input amplifier 400, the filter 405, the chirp generator410, the mixer 415, the data extractor 420, the demodulated signal data425, the transmitter 430, the network 435, the configuration selector440, the configuration selection data 445, the database 450, and thepresentation device 455 of FIG. 4 described above. Thus, in the interestof brevity, the structure, function and/or operation of thesecomponents, structures and data of the acoustic emission sensor 200 ofFIG. 5 are not repeated herein.

While an example manner of implementing the example acoustic emissionsensor 200, the example pre-amplifier 202, and the example AED 100 ofFIG. 2 is illustrated in FIG. 5, one or more of the elements, processesand/or devices illustrated in FIG. 5 may be combined, divided,re-arranged, omitted, eliminated and/or implemented in any other way.Further, the example AED 100, the example pre-amplifier 202, the exampleinput amplifier 400, the example filter 405, the example chirp generator410, the example mixer 415, the example data extractor 420, the exampletransmitter 430, the example configuration selector 440, the exampledatabase 450, the example presentation device 455, and/or, moregenerally, the example acoustic emission sensor 200 of FIG. 5 may beimplemented by hardware, software, firmware and/or any combination ofhardware, software and/or firmware. Thus, for example, any of theexample AED 100, the example pre-amplifier 202, the example inputamplifier 400, the example filter 405, the example chirp generator 410,the example mixer 415, the example data extractor 420, the exampletransmitter 430, the example configuration selector 440, the exampledatabase 450, the example presentation device 455, and/or, moregenerally, the example acoustic emission sensor 102 could be implementedby one or more analog or digital circuit(s), logic circuits,programmable processor(s), application specific integrated circuit(s)(ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)). When reading any of theapparatus or system claims of this patent to cover a purely softwareand/or firmware implementation, at least one of the example AED 100, theexample pre-amplifier 202, the example input amplifier 400, the examplefilter 405, the example chirp generator 410, the example mixer 415, theexample data extractor 420, the example transmitter 430, the exampleconfiguration selector 440, the example database 450, and/or the examplepresentation device 455 is/are hereby expressly defined to include anon-transitory computer readable storage device or storage disk such asa memory, a digital versatile disk (DVD), a compact disk (CD), a Blu-raydisk, etc. including the software and/or firmware. Further still, theexample acoustic emission sensor 200 of FIG. 2 may include one or moreelements, processes and/or devices in addition to, or instead of, thoseillustrated in FIG. 5, and/or may include more than one of any or all ofthe illustrated elements, processes and devices.

FIG. 6 is a block diagram of an example implementation of the exampleAED 100 of FIGS. 1-5, and the example pre-amplifier 300 and the exampleacoustic emission sensor 302 of FIG. 3 in accordance with the teachingsof this disclosure. In the illustrated example, the pre-amplifier 300 isnot included in or integrated with the acoustic emission sensor 302. Forexample, the acoustic emission sensor 302 may generate the acousticemission signal 108 of FIGS. 1-5 based on the sensing element 110 ofFIGS. 1-5 sensing, measuring, and/or detecting the acoustic emission 408of FIGS. 4-5. In such an example, the acoustic emission sensor 302 maytransmit the acoustic emission signal 108 to the pre-amplifier 300 viathe cable 126 of FIG. 3.

In the illustrated example, the pre-amplifier 300 generatespre-amplified acoustic emission data via the input amplifier 400 and thefilter 405. The AED 100 of the illustrated example uses the dataextractor 420 to generate the demodulated signal data 425 based on themixed acoustic emission data obtained from the mixer 415. Alternatively,the example AED 100 may process the example acoustic emission signal 108prior to the example input amplifier 400 and/or the example filter 405conditioning the acoustic emission signal 108. In the illustratedexample, the pre-amplifier 300 transmits information (e.g., acousticemission signal 108, the demodulated signal data 425, etc.) to the dataacquisition system 124 via the transmitter 430. Alternatively, theexample transmitter 430 and/or the example database 450 may beintegrated into the example AED 100.

In connection with the illustrated example of FIG. 6, the structure,function, and/or operation of each of the AED 100, the input amplifier400, the filter 405, the chirp generator 410, the mixer 415, the dataextractor 420, the demodulated signal data 425, the transmitter 430, thenetwork 435, the configuration selector 440, the configuration selectiondata 445, the database 450, and the presentation device 455 is/are thesame as the corresponding structure, function, and/or operation of theAED 100, the input amplifier 400, the filter 405, the chirp generator410, the mixer 415, the data extractor 420, the demodulated signal data425, the transmitter 430, the network 435, the configuration selector440, the configuration selection data 445, the database 450, and thepresentation device 455 of FIGS. 4-5 described above. Thus, in theinterest of brevity, the structure, function and/or operation of thesecomponents, structures and data of the pre-amplifier 300 of FIG. 6 arenot repeated herein.

While an example manner of implementing the example pre-amplifier 300and the AED 100 of FIG. 3 is illustrated in FIG. 6, one or more of theelements, processes and/or devices illustrated in FIG. 6 may becombined, divided, re-arranged, omitted, eliminated and/or implementedin any other way. Further, the example AED 100, the example inputamplifier 400, the example filter 405, the example chirp generator 410,the example mixer 415, the example data extractor 420, the exampletransmitter 430, the example configuration selector 440, the exampledatabase 450, the example presentation device 455, and/or, moregenerally, the example pre-amplifier 300 of FIG. 6 may be implemented byhardware, software, firmware and/or any combination of hardware,software and/or firmware. Thus, for example, any of the example AED 100,the example input amplifier 400, the example filter 405, the examplechirp generator 410, the example mixer 415, the example data extractor420, the example transmitter 430, the example configuration selector440, the example database 450, the example presentation device 455,and/or, more generally, the example pre-amplifier 300 of FIG. 6 could beimplemented by one or more analog or digital circuit(s), logic circuits,programmable processor(s), application specific integrated circuit(s)(ASIC(s)), programmable logic device(s) (PLD(s)) and/or fieldprogrammable logic device(s) (FPLD(s)). When reading any of theapparatus or system claims of this patent to cover a purely softwareand/or firmware implementation, at least one of the example AED 100, theexample input amplifier 400, the example filter 405, the example chirpgenerator 410, the example mixer 415, the example data extractor 420,the example transmitter 430, the example configuration selector 440, theexample database 450, and the example presentation device 455, is/arehereby expressly defined to include a non-transitory computer readablestorage device or storage disk such as a memory, a digital versatiledisk (DVD), a compact disk (CD), a Blu-ray disk, etc. including thesoftware and/or firmware. Further still, the example pre-amplifier 300of FIG. 6 may include one or more elements, processes and/or devices inaddition to, or instead of, those illustrated in FIG. 6, and/or mayinclude more than one of any or all of the illustrated elements,processes and devices.

Flowcharts representative of example methods for implementing theexample acoustic emission sensor 102 of FIG. 1, the example acousticemission sensor 200 of FIG. 2, and/or the example pre-amplifier 300 ofFIG. 3 are shown in FIGS. 7-9. In these examples, the methods may beimplemented using machine readable instructions which comprise a programfor execution by a processor such as a first processor 1112 shown in theexample processor platform 1100 discussed below in connection with FIG.11, a second processor 1212 shown in the example processor platform 1200discussed below in connection with FIG. 12, and/or a third processor1312 shown in the example processor platform 1300 discussed below inconnection with FIG. 13. The program may be embodied in software storedon a non-transitory computer readable storage medium such as a CD-ROM, afloppy disk, a hard drive, a DVD, a Blu-ray disk, or a memory associatedwith the processors 1112, 1212, 1312, but the entire program and/orparts thereof could alternatively be executed by a device other than theprocessors 1112, 1212, 1312, and/or embodied in firmware or dedicatedhardware. Further, although the example program is described withreference to the flowcharts illustrated in FIGS. 7-9, many other methodsof implementing the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 may alternatively be used. For example, theorder of execution of the blocks may be changed, and/or some of theblocks described may be changed, eliminated, or combined. Additionallyor alternatively, any or all of the blocks may be implemented by one ormore hardware circuits (e.g., discrete and/or integrated analog and/ordigital circuitry, a Field Programmable Gate Array (FPGA), anApplication Specific Integrated circuit (ASIC), a comparator, anoperational-amplifier (op-amp), a logic circuit, etc.) structured toperform the corresponding operation without executing software orfirmware.

As mentioned above, the example processes of FIGS. 7-9 may beimplemented using coded instructions (e.g., computer and/or machinereadable instructions) stored on a non-transitory computer and/ormachine readable medium such as a hard disk drive, a flash memory, aread-only memory, a CD, a DVD, a cache, a random-access memory and/orany other storage device or storage disk in which information is storedfor any duration (e.g., for extended time periods, permanently, forbrief instances, for temporarily buffering, and/or for caching of theinformation). As used herein, the term non-transitory computer readablemedium is expressly defined to include any type of computer readablestorage device and/or storage disk and to exclude propagating signalsand to exclude transmission media. “Including” and “comprising” (and allforms and tenses thereof) are used herein to be open ended terms. Thus,whenever a claim lists anything following any form of “include” or“comprise” (e.g., comprises, includes, comprising, including, etc.), itis to be understood that additional elements, terms, etc. may be presentwithout falling outside the scope of the corresponding claim. As usedherein, when the phrase “at least” is used as the transition term in apreamble of a claim, it is open ended in the same manner as the term“comprising” and “including” are open ended.

FIG. 7 is a flowchart representative of an example method 700 that maybe performed by the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 to generate demodulated acoustic emissiondata. The example method 700 begins at block 702 when the exampleacoustic emission sensors 102, 200 of FIGS. 1-2 and/or the pre-amplifier300 of FIG. 3 obtain configuration selection data. For example, theconfiguration selector 440 of FIGS. 4-6 may obtain the configurationselection data 445 of FIGS. 4-6 from the data acquisition system 124 ofFIGS. 1-6 via the network 435 of FIGS. 4-6.

At block 704, the example acoustic emission sensors 102, 200 of FIGS.1-2 and/or the pre-amplifier 300 of FIG. 3 configure components. Forexample, the configuration selector 440 of FIGS. 4-6 may configure oneor more of the input amplifier 400, the filter 405, the chirp generator410, the transmitter 430, etc., of FIGS. 4-6 based on the obtainedconfiguration selection data 445. An example process that may be used toimplement block 704 is described below in connection with FIG. 8.

At block 706, the example acoustic emission sensors 102, 200, 302 ofFIGS. 1-3 generate an acoustic emission signal. For example, theacoustic emission sensor 102 of FIG. 1 may generate the acousticemission signal 108 of FIG. 1 in response to acoustic emissions (e.g.,transient elastic waves from an acoustic emission source) sensed,measured, and/or detected via a sensing element (e.g., one or morepiezoelectric crystals) of the acoustic emission sensor 102.

At block 708, the example acoustic emission sensors 102, 200 of FIGS.1-2 and/or the pre-amplifier 300 of FIG. 3 generate demodulated acousticemission data based on a filtered mixed acoustic emission signal. Forexample, the AED 100 of FIGS. 1-6 may generate a chirp signal thatincreases or decreases in frequency with respect to time via the chirpgenerator 410 of FIGS. 4-6. In such an example, the AED 100 may combinethe chirp signal with a pre-amplified acoustic emission signal via themixer 415 of FIGS. 4-6 to generate a mixed acoustic emission signal. Insuch an example, the AED 100 may filter the mixed acoustic emissionsignal to generate a filtered mixed acoustic emission signal via thedata extractor 420. In such an example, the AED 100 may extractdemodulated acoustic emission data such as spectral data, time-averageddata, etc., and/or a combination thereof from the mixed acousticemission signal via the data extractor 420. An example process that maybe used to implement block 708 is described below in connection withFIG. 9.

At block 710, the example acoustic emission sensors 102, 200 of FIGS.1-2 and/or the pre-amplifier 300 of FIG. 3 transmit the demodulatedacoustic emission data to an external data acquisition system. Forexample, the transmitter 430 of FIGS. 4-6 may transmit the spectraldata, the time-averaged data, etc., and/or a combination thereof to thedata acquisition system 124 of FIGS. 1-6. In response to transmittingthe demodulated acoustic emission data to the external data acquisitionsystem, the example method 700 concludes.

FIG. 8 is a flowchart representative of an example method 800 that maybe performed by the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 to configure one or more components used togenerate acoustic emission spectral data. The example process of FIG. 8may be used to implement the operation of block 704 of FIG. 7. Theexample method 800 begins at block 802 when the example acousticemission sensors 102, 200 of FIGS. 1-2 and/or the pre-amplifier 300 ofFIG. 3 compare obtained configuration selection data to storedconfiguration selection data. For example, the configuration selector440 of FIGS. 4-6 may compare a first value of a sweep time for the chirpgenerator 410 of FIGS. 4-6 to a second value of the sweep time stored inthe database 450 of FIGS. 4-6.

At block 804, the example acoustic emission sensors 102, 200 of FIGS.1-2 and/or the pre-amplifier 300 of FIG. 3 determine whether theobtained configuration selection data is different than the storedconfiguration selection data. For example, the configuration selector440 of FIGS. 4-6 may store the first value in place of the second valuein the database 450 of FIGS. 4-6 when the first and the second valuesare different. In another example, the configuration selector 440 maydiscard the first value when the first and the second values are thesame.

If, at block 804, the example acoustic emission sensors 102, 200 ofFIGS. 1-2 and/or the pre-amplifier 300 of FIG. 3 determine that theobtained configuration selection data is not different than the storedconfiguration selection data, the example method 800 concludes. If, atblock 804, the example acoustic emission sensors 102, 200 of FIGS. 1-2and/or the pre-amplifier 300 of FIG. 3 determine that the obtainedconfiguration selection data is different than the stored configurationselection data, then, at block 806, the example acoustic emissionsensors 102, 200 of FIGS. 1-2 and/or the pre-amplifier 300 of FIG. 3store the obtained configuration selection data. For example, theconfiguration selector 440 of FIGS. 4-6 may store the first value of thesweep time in place of the second value of the sweep time when the firstand the second values are different.

At block 808, the example acoustic emission sensors 102, 200 of FIGS.1-2 and/or the pre-amplifier 300 of FIG. 3 configure one or moreamplifiers. For example, the configuration selector 440 of FIG. 4 mayconfigure a gain of the input amplifier 400 of FIG. 4 based on a storedvalue of the gain in the database 450 of FIG. 4.

At block 810, the example acoustic emission sensors 102, 200 of FIGS.1-2 and/or the pre-amplifier 300 of FIG. 3 configure a chirp generator.For example, the configuration selector 440 of FIG. 4 may configure astart frequency value, an end frequency value, a sweep time value, etc.,of the chirp generator 410 of FIG. 4 based on a stored value of thestart frequency value, the end frequency value, the sweep time value,etc., in the database 450 of FIG. 4.

At block 812, the example acoustic emission sensors 102, 200 of FIGS.1-2 and/or the pre-amplifier 300 of FIG. 3 configure a transmitter. Forexample, the configuration selector 440 of FIG. 4 may configure an IPaddress and a port number of the transmitter 430 to utilizeEthernet-based communication. In response to the example acousticemission sensors 102, 200 of FIGS. 1-2 and/or the pre-amplifier 300 ofFIG. 3 configuring the transmitter, the example method 800 concludes.

FIG. 9 is a flowchart representative of an example method 900 that maybe performed by the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 to generate demodulated acoustic emissiondata. The example process of FIG. 9 may be used to implement theoperation of block 708 of FIG. 7. The example method 900 begins at block902 when the example acoustic emission sensor 102 of FIG. 1, the exampleacoustic emission sensor 200 of FIG. 2, and/or the example pre-amplifier300 of FIG. 3 generate chirp signal(s) based on a start frequency value,an end frequency value, and a sweep time value. For example, the chirpgenerator 410 of FIGS. 4-6 may generate a first chirp signal increasingin frequency with respect to time based on a start frequency value of9.55 MHz, an end frequency value of 9.95 MHz, and a sweep time value of100 milliseconds. For example, the chirp generator 410 may generate thefirst chirp signal at the start frequency value of 9.55 MHz,subsequently increasing in frequency up to and including 9.95 MHz.

At block 904, the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 combine a pre-amplified acoustic emissionsignal with the chirp signal(s) to generate a mixed acoustic emissionsignal. For example, the mixer 415 of FIGS. 4-6 may combine apre-amplified acoustic emission signal based on the acoustic emissionsignal 108 of FIGS. 1-6 with the first chirp signal to generate a mixedacoustic emission signal. For example, the mixer 415 may combine apre-amplified acoustic emission signal 1006 of FIG. 10A with a chirpsignal 1016 of FIG. 10B at a frequency value of 9.75 MHz to generate afirst and a second single sideband 1010, 1012 of a mixed acousticemission signal 1014.

At block 906, the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 filter the mixed acoustic emission signal togenerate a filtered mixed acoustic emission signal. For example, thedata extractor 420 of FIGS. 4-6 may remove spectral information from themixed acoustic emission signal obtained from the mixer 415 of FIGS. 4-6.For example, the data extractor 420 of FIGS. 4-6 may include a band-passfilter to remove spectral information outside of a frequency range of9.75 MHz to 10.25 MHz from the mixed acoustic emission signal. Forexample, the data extractor 420 may use a band-pass filter to isolatethe first or the second single sidebands 1010, 1012 of FIG. 10B to onlyinclude the mixed acoustic emission signal 1014 of FIG. 10B within thefrequency range of 9.75 MHz to 10.25 MHz to generate a filtered mixedacoustic emission signal 1018 as depicted in FIG. 10C. Additionally oralternatively, the data extractor 420 may filter the mixed acousticemission signal 1014 of FIG. 10B within the intermediate bandwidth 1008of FIG. 10C with respect to a 10 MHz intermediate center frequency 1020to generate a filtered mixed acoustic emission signal 1018 as depictedin FIG. 10C.

At block 908, the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 extract demodulated acoustic emission datafrom the filtered mixed acoustic emission signal. For example, the dataextractor 420 of FIGS. 4-6 may generate the demodulated signal data 425of FIGS. 4-6 that includes spectral data, time-averaged data, etc., thatincludes root mean square data, average signal level data, etc. In suchan example, the demodulated signal data 425 of FIGS. 4-6 may include anamplitude, an energy, frequency information, ASL data, RMS data, etc.,corresponding to the acoustic emission signal 108 of FIGS. 1-6. Forexample, the data extractor 420 may sample the filtered mixed acousticemission signal 1018 of FIG. 10C at an intermediate center frequency1020 of 10 MHz within the intermediate frequency bandwidth 1008 of 50kHz.

At block 910, the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 correlate extracted demodulated acousticemission data to measurement center frequency to generate a spectrum ofan acoustic emission signal. For example, the data extractor 420 may mapthe sample of the spectral information of the second single sidebandacoustic emission signal 1012 of FIG. 10C to the measurement centerfrequency 1002 of FIG. 10A to generate spectral information. The exampledata extractor 420 may aggregate the spectral information for aplurality of samples of spectral information for a plurality ofmeasurement center frequencies based on a chirp signal increasing ordecreasing in frequency within a range of 9.55 MHz to 9.95 MHz togenerate a low-resolution and high-bandwidth spectrum 1022 (e.g.,demodulated acoustic emission data 1022) of FIG. 10D.

At block 912, the example acoustic emission sensor 102 of FIG. 1, theexample acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 determine whether to generate chirp signalsusing another frequency range of interest. For example, the chirpgenerator 410 may determine to generate second chirp signals increasingin frequency with respect to time based on a second start frequencyvalue of 50 kHz, a second end frequency value of 450 kHz, and a secondsweep time value of 150 milliseconds.

If, at block 912, the example acoustic emission sensor 102 of FIG. 1,the example acoustic emission sensor 200 of FIG. 2, and/or the examplepre-amplifier 300 of FIG. 3 determine that there is another frequencyrange of interest, control returns to block 902 to generate anotherchirp signal at another frequency range of interest (e.g., chirp signalsbased on the second start frequency value, the second end frequencyvalue, the second sweep time value, etc., and/or a combination thereof),otherwise the example method 900 concludes.

FIG. 10A is an example graph depicting the example measurement centerfrequency 1002 within the example measurement bandwidth 1004 of theexample acoustic emission signal 1006 as a function of frequency andamplitude. In the illustrated example, the measurement center frequency1002 is 250 kHz within an intermediate frequency bandwidth 1008.Alternatively, any other measurement center frequency may be used. Inthe illustrated example, the intermediate frequency bandwidth 1008 is 50kHz. Alternatively, any other intermediate frequency bandwidth may beused. The measurement center frequency 1002 of the illustrated examplerepresents a measure of a central frequency between a lower and an uppercutoff of the measurement bandwidth 1004. In the illustrated example,the measurement bandwidth 1004 is 50-450 kHz. Alternatively, any othermeasurement bandwidth may be used. The measurement bandwidth 1004 of theillustrated example represents a measurement range of interest for theacoustic emission signal 1006. For example, the acoustic emission signal1006 of the illustrated example may correspond to the acoustic emissionsignal 108 of FIGS. 4-6.

FIG. 10B is an example graph depicting the first and the secondsidebands 1010, 1012 of the mixed acoustic emission signal 1014. In theillustrated example, the first and the second sidebands 1010, 1012 areshifted away from the measurement center frequency 1002 of FIG. 10Abased on the AED 100 of FIGS. 1-6 (e.g., the mixer 415 of FIGS. 4-6)combining the chirp signal 1016 of FIG. 10B with the acoustic emissionsignal 1006 of FIG. 10A. The first sideband 1010 of the illustratedexample is a mirror of the second sideband 1012 about the chirp signal1016 at a chirp frequency of 9.75 MHz.

FIG. 10C is an example graph depicting the filtered mixed acousticemission signal 1018 as a function of frequency and amplitude. In theillustrated example of FIG. 10C, the AED 100 of FIGS. 1-6 (e.g., thedata extractor 420 of FIGS. 4-6) generates the filtered mixed acousticemission signal 1018 by isolating data included in the mixed acousticemission signal 1014 of FIG. 10B within the range of 9.75 MHz to 10.25MHz. In the illustrated example, the AED 100 of FIGS. 1-6 (e.g., thedata extractor 420 of FIGS. 4-6) is sampling spectral information of thefiltered mixed acoustic emission signal 1018 at the intermediate centerfrequency 1020 within the intermediate frequency bandwidth 1008 of FIG.10A. In the illustrated example of FIG. 10C, the intermediate centerfrequency 1020 is 10 MHz. Alternatively, any other intermediate centerfrequency may be used. In the illustrated example of FIG. 10C, theintermediate frequency bandwidth 1008 is 50 kHz. Alternatively, anyother intermediate frequency bandwidth may be used.

FIG. 10D is an example graph depicting the example demodulated acousticemission data 1022 as a function of frequency and amplitude. The exampledemodulated acoustic emission data 1022 of FIG. 10D is based on at leastthe sampling of the spectral information of the second single sideband1012 of FIG. 10B. In the illustrated example of FIG. 10D, thedemodulated acoustic emission data 1022 is a low-resolution andhigh-bandwidth spectrum of the acoustic emission signal 1006 of FIG.10A. The demodulated acoustic emission data 1022 of FIG. 10D can beprocessed by the AED 100 of FIGS. 1-6 (e.g., the data extractor 420 ofFIGS. 4-6) to generate ASL data, RMS data, etc.

In the illustrated example of FIG. 10D, the AED 100 generates thedemodulated acoustic emission data 1022 representing a spectrum of theacoustic emission signal 1006 based on increasing (e.g., continuouslyincreasing) or decreasing (e.g., continuously decreasing) the frequencyof the chirp signal 1016 within the measurement bandwidth 1004,generating pairs of single sideband acoustic emission signals based onthe chirp frequency, and sampling spectral information corresponding tothe generated pairs of single sideband acoustic emission signals.

FIGS. 10A-10D are example representations of processing the acousticemission signal 1006 using the chirp signal 1016. In response to thechirp signal 1016 moving continuously from the start frequency to theend frequency, the measurement center point is swept through themeasurement bandwidth 1004 of FIG. 10A. At the instantaneous chirpfrequency, the example AED 100 generates the pair of single sidebands1010, 1012 of the mixed acoustic emission signal 1014 as illustrated inFIG. 10B. In response to generating the pair of single sidebands 1010,1012, the example AED 100 filters the mixed acoustic emission signal1014 to generate the filtered mixed acoustic emission signal 1018 asillustrated in FIG. 10C, and samples spectral information correspondingto the filtered mixed acoustic emission signal 1018 as illustrated inFIG. 10C. The spectral information corresponding to the measurementbandwidth 1004 of FIG. 10A can be processed by the example AED 100 andrepresented as the demodulated acoustic emission data 1022 asillustrated in FIG. 10D.

In some examples, in response to the measurement center point sweepingthrough the measurement bandwidth 1004, the example AED 100 adjusts themeasurement bandwidth 1004 to another measurement bandwidth. Forexample, the chirp generator 410 may adjust the measurement bandwidthfrom 50-450 kHz to 450 kHz to 900 kHz. The example AED 100 may generatedemodulated acoustic emission data as described above in the adjustedmeasurement bandwidth of 450 kHz to 900 kHz. By adjusting (e.g.,iteratively adjusting) the measurement bandwidth to encompass ameasurement range of interest for the acoustic emission signal 1006, theexample AED 100 may generate a low-resolution and high-bandwidthspectrum of the acoustic emission signal 1006 as illustrated in FIG.10D.

FIG. 11 is a block diagram of an example processor platform 1100 capableof executing instructions to implement the methods of FIGS. 7-9 and theexample acoustic emission sensor 102 of FIG. 1. The processor platform1100 of the illustrated example includes a processor 1112. The processor1112 of the illustrated example is hardware. For example, the processor1112 can be implemented by one or more integrated circuits, logiccircuits, microprocessors or controllers from any desired family ormanufacturer. The hardware processor may be a semiconductor based (e.g.,silicon based) device. In this example, the processor 1112 implementsthe example AED 100, the example pre-amplifier 112, the example inputamplifier 400, the example filter 405, the example chirp generator 410,the example mixer 415, the example data extractor 420, and the exampleconfiguration selector 440 of FIG. 4.

The processor 1112 of the illustrated example includes a local memory1113 (e.g., a cache). The processor 1112 of the illustrated example isin communication with a main memory including a volatile memory 1114 anda non-volatile memory 1116 via a bus 1118. The volatile memory 1114 maybe implemented by Synchronous Dynamic Random Access Memory (SDRAM),Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory(RDRAM) and/or any other type of random access memory device. Thenon-volatile memory 1116 may be implemented by flash memory and/or anyother desired type of memory device. Access to the main memory 1114,1116 is controlled by a memory controller.

The processor platform 1100 of the illustrated example also includes aninterface circuit 1120. The interface circuit 1120 may be implemented byany type of interface standard, such as an Ethernet interface, auniversal serial bus (USB), and/or a peripheral component interconnect(PCI) express interface.

One or more output devices 1124 are connected to the interface circuit1120 of the illustrated example. The output devices 1124 can beimplemented, for example, by display devices (e.g., a light emittingdiode (LED), an organic light emitting diode (OLED), a liquid crystaldisplay, a cathode ray tube display (CRT), a touchscreen, a tactileoutput device, a printer and/or speakers). The interface circuit 1120 ofthe illustrated example, thus, typically includes a graphics drivercard, a graphics driver chip and/or a graphics driver processor. Theoutput device 1124 implements the example presentation device 455 ofFIG. 4.

The interface circuit 1120 of the illustrated example also includes acommunication device such as a transmitter, a receiver, a transceiver, amodem and/or network interface card to facilitate exchange of data withexternal machines (e.g., computing devices of any kind) such as the dataacquisition system 124 of FIGS. 1-6 via a network 1126 (e.g., anEthernet connection, a digital subscriber line (DSL), a telephone line,coaxial cable, a cellular telephone system, etc.). The interface circuit1120 implements the example transmitter 430 of FIG. 4. The network 1126implements the example network 435 of FIG. 4.

The processor platform 1100 of the illustrated example also includes oneor more mass storage devices 1128 for storing software and/or data.Examples of such mass storage devices 1028 include floppy disk drives,hard drive disks, compact disk drives, Blu-ray disk drives, redundantarray of independent disks (RAID) systems, and DVD drives. The massstorage device 1128 implements the example database 450 of FIG. 4.

Coded instructions 1132 to implement the methods of FIGS. 7-9 may bestored in the mass storage device 1128, in the volatile memory 1114, inthe non-volatile memory 1116, and/or on a removable non-transitorycomputer readable storage medium such as a CD or DVD.

FIG. 12 is a block diagram of an example processor platform 1200 capableof executing instructions to implement the methods of FIGS. 7-9 and theexample acoustic emission sensor 200 of FIG. 2. The processor platform1200 of the illustrated example includes a processor 1212. The processor1212 of the illustrated example is hardware. For example, the processor1212 can be implemented by one or more integrated circuits, logiccircuits, microprocessors or controllers from any desired family ormanufacturer. The hardware processor may be a semiconductor based (e.g.,silicon based) device. In this example, the processor 1212 implementsthe example AED 100, the example pre-amplifier 202, the example inputamplifier 400, the example filter 405, the example chirp generator 410,the example mixer 415, the example data extractor 420, and the exampleconfiguration selector 440 of FIG. 5.

The processor 1212 of the illustrated example includes a local memory1213 (e.g., a cache). The processor 1212 of the illustrated example isin communication with a main memory including a volatile memory 1214 anda non-volatile memory 1216 via a bus 1218. The volatile memory 1214 maybe implemented by Synchronous Dynamic Random Access Memory (SDRAM),Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory(RDRAM) and/or any other type of random access memory device. Thenon-volatile memory 1216 may be implemented by flash memory and/or anyother desired type of memory device. Access to the main memory 1214,1216 is controlled by a memory controller.

The processor platform 1200 of the illustrated example also includes aninterface circuit 1220. The interface circuit 1220 may be implemented byany type of interface standard, such as an Ethernet interface, auniversal serial bus (USB), and/or a peripheral component interconnect(PCI) express interface.

One or more output devices 1224 are connected to the interface circuit1220 of the illustrated example. The output devices 1224 can beimplemented, for example, by display devices (e.g., a light emittingdiode (LED), an organic light emitting diode (OLED), a liquid crystaldisplay, a cathode ray tube display (CRT), a touchscreen, a tactileoutput device, a printer and/or speakers). The interface circuit 1220 ofthe illustrated example, thus, typically includes a graphics drivercard, a graphics driver chip and/or a graphics driver processor. Theoutput device 1224 implements the example presentation device 455 ofFIG. 5.

The interface circuit 1220 of the illustrated example also includes acommunication device such as a transmitter, a receiver, a transceiver, amodem and/or network interface card to facilitate exchange of data withexternal machines (e.g., computing devices of any kind) such as the dataacquisition system 124 of FIGS. 1-6 via a network 1226 (e.g., anEthernet connection, a digital subscriber line (DSL), a telephone line,coaxial cable, a cellular telephone system, etc.). The interface circuit1220 implements the example transmitter 430 of FIG. 5. The network 1226implements the example network 435 of FIG. 5.

The processor platform 1200 of the illustrated example also includes oneor more mass storage devices 1228 for storing software and/or data.Examples of such mass storage devices 1228 include floppy disk drives,hard drive disks, compact disk drives, Blu-ray disk drives, redundantarray of independent disks (RAID) systems, and DVD drives. The massstorage device 1228 implements the example database 450 of FIG. 5.

Coded instructions 1232 to implement the methods of FIGS. 7-9 may bestored in the mass storage device 1228, in the volatile memory 1214, inthe non-volatile memory 1216, and/or on a removable non-transitorycomputer readable storage medium such as a CD or DVD.

FIG. 13 is a block diagram of an example processor platform 1300 capableof executing instructions to implement the methods of FIGS. 7-9 and theexample pre-amplifier 300 of FIG. 3. The processor platform 1300 of theillustrated example includes a processor 1312. The processor 1312 of theillustrated example is hardware. For example, the processor 1312 can beimplemented by one or more integrated circuits, logic circuits,microprocessors or controllers from any desired family or manufacturer.The hardware processor may be a semiconductor based (e.g., siliconbased) device. In this example, the processor 1312 implements theexample AED 100, the example input amplifier 400, the example filter405, the example chirp generator 410, the example mixer 415, the exampledata extractor 420, and the example configuration selector 440 of FIG.6.

The processor 1312 of the illustrated example includes a local memory1313 (e.g., a cache). The processor 1312 of the illustrated example isin communication with a main memory including a volatile memory 1314 anda non-volatile memory 1316 via a bus 1318. The volatile memory 1314 maybe implemented by Synchronous Dynamic Random Access Memory (SDRAM),Dynamic Random Access Memory (DRAM), RAMBUS Dynamic Random Access Memory(RDRAM) and/or any other type of random access memory device. Thenon-volatile memory 1316 may be implemented by flash memory and/or anyother desired type of memory device. Access to the main memory 1314,1316 is controlled by a memory controller.

The processor platform 1300 of the illustrated example also includes aninterface circuit 1320. The interface circuit 1320 may be implemented byany type of interface standard, such as an Ethernet interface, auniversal serial bus (USB), and/or a peripheral component interconnect(PCI) express interface.

One or more output devices 1324 are connected to the interface circuit1320 of the illustrated example. The output devices 1324 can beimplemented, for example, by display devices (e.g., a light emittingdiode (LED), an organic light emitting diode (OLED), a liquid crystaldisplay, a cathode ray tube display (CRT), a touchscreen, a tactileoutput device, a printer and/or speakers). The interface circuit 1320 ofthe illustrated example, thus, typically includes a graphics drivercard, a graphics driver chip and/or a graphics driver processor. Theoutput device 1324 implements the example presentation device 455 ofFIG. 6.

The interface circuit 1320 of the illustrated example also includes acommunication device such as a transmitter, a receiver, a transceiver, amodem and/or network interface card to facilitate exchange of data withexternal machines (e.g., computing devices of any kind) such as the dataacquisition system 124 of FIGS. 1-6 via a network 1326 (e.g., anEthernet connection, a digital subscriber line (DSL), a telephone line,coaxial cable, a cellular telephone system, etc.). The interface circuit1320 implements the example transmitter 430 of FIG. 6. The network 1326implements the example network 435 of FIG. 6.

The processor platform 1300 of the illustrated example also includes oneor more mass storage devices 1328 for storing software and/or data.Examples of such mass storage devices 1328 include floppy disk drives,hard drive disks, compact disk drives, Blu-ray disk drives, redundantarray of independent disks (RAID) systems, and DVD drives. The massstorage device 1328 implements the example database 450 of FIG. 6.

Coded instructions 1332 to implement the methods of FIGS. 7-9 may bestored in the mass storage device 1328, in the volatile memory 1314, inthe non-volatile memory 1316, and/or on a removable non-transitorycomputer readable storage medium such as a CD or DVD.

From the foregoing, it will be appreciated that example methods,apparatus and articles of manufacture have been disclosed that generatean acoustic emission spectrum using chirp demodulation. Theabove-disclosed integrated acoustic emission sensor apparatus andintegrated acoustic emission pre-amplifier apparatus reduce the need forhigh-speed sampling and extensive post processing operations to producedemodulated acoustic emission data. By integrating an acoustic emissiondemodulator (AED) apparatus into an acoustic emission sensor and/or anacoustic emission pre-amplifier, frequency information corresponding toa continuous acoustic emission source can be generated without digitallysampling the continuous acoustic emissions at high rates. In addition,by integrating the above-disclosed AED apparatus into the acousticemission sensor and/or the acoustic emission pre-amplifier, availableprocessing power and/or memory resources can be reduced or reallocatedto complete additional computing tasks.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

What is claimed is:
 1. An integrated acoustic emission sensorcomprising: a pre-amplifier to condition an acoustic emission signal togenerate a pre-amplified acoustic emission signal, the acoustic emissionsignal based on an acoustic emission source; a demodulator to: generatea chirp signal based on at least one of a start frequency, an endfrequency, or a sweep time; combine the pre-amplified acoustic emissionsignal with the chirp signal to generate a sideband acoustic emissionsignal; sample spectral data of the sideband acoustic emission signal atan intermediate center frequency in an intermediate frequency bandwidth;and generate demodulated acoustic emission data based on mapping thesampled spectral data to a measurement center frequency to generate alow-resolution and high-bandwidth spectrum, the measurement centerfrequency different from the intermediate center frequency; and atransmitter to transmit the demodulated acoustic emission data to a dataacquisition system.
 2. The integrated acoustic emission sensor of claim1, wherein the pre-amplifier includes an amplifier to strengthen theacoustic emission signal and a filter to remove frequency informationnot within a frequency bandwidth.
 3. The integrated acoustic emissionsensor of claim 1, the demodulator further including: a chirp generatorto generate the chirp signal based on at least one of the startfrequency, the end frequency, or the sweep time; and a mixer to combinethe chirp signal with the acoustic emission signal to generate mixedacoustic emission data, the mixed acoustic emission data including thesideband acoustic emission signal; and a data extractor to: filter themixed acoustic emission data based on a filter bandwidth to generatefiltered mixed acoustic emission data; and convert the filtered mixedacoustic emission data to the demodulated acoustic emission data.
 4. Theintegrated acoustic emission sensor of claim 1, wherein the demodulatedacoustic emission data includes at least one of the spectral data ortime-averaged data to characterize the acoustic emission source during ameasurement time period, the spectral data or the time-averaged dataincluding at least one of a voltage amplitude, an energy value, or afrequency value, and the demodulator further including a data extractorto generate an alert in response to the at least one of the voltageamplitude, the energy value, or the frequency value satisfying athreshold.
 5. The integrated acoustic emission sensor of claim 1,wherein data the demodulator further includes: a chirp generator togenerate the chirp signal at a first instantaneous frequency; a mixer tocombine (1) the chirp signal at the first instantaneous frequency and(2) the pre-amplified acoustic emission signal corresponding to ameasurement bandwidth to generate the sideband acoustic emission signal,the sideband acoustic emission signal shifted away from the measurementbandwidth based on the first instantaneous frequency; a data extractorto sample the spectral data at the intermediate center frequency, theintermediate center frequency based on the first instantaneous frequencyand the measurement bandwidth; and a configuration selector to selectthe measurement bandwidth.
 6. The integrated acoustic emission sensor ofclaim 1, further including a configuration selector to adjust aparameter of at least one of the pre-amplifier or the demodulator by atleast one of modifying a gain of an amplifier, a bandwidth of a filter,a start frequency value of a chirp generator, an end frequency value ofthe chirp generator, a sweep time value of the chirp generator, or acommunication parameter of the transmitter.
 7. The integrated acousticemission sensor of claim 1, further including a presentation device todisplay the demodulated acoustic emission data.
 8. A method comprising:conditioning an acoustic emission signal based on an acoustic emissionsource with a pre-amplifier integrated into an acoustic emission sensorto generate a pre-amplified acoustic emission signal; generating a chirpsignal based on at least one of a start frequency, an end frequency, ora sweep time; combining the pre-amplified acoustic emission signal withthe chirp signal to generate a sideband acoustic emission signal;sampling spectral data of the sideband acoustic emission signal at anintermediate center frequency in an intermediate frequency bandwidth;generating demodulated acoustic emission data based on mapping thesampled spectral data to a measurement center frequency to generate alow-resolution and high-bandwidth spectrum, the measurement centerfrequency different from the intermediate center frequency; andtransmitting the demodulated acoustic emission data to a dataacquisition system.
 9. The method of claim 8, wherein conditioning theacoustic emission signal includes at least one of strengthening theacoustic emission signal with an amplifier or removing frequencyinformation not within a frequency bandwidth with a filter.
 10. Themethod of claim 8, wherein the demodulated acoustic emission dataincludes at least one of the spectral data or time-averaged data tocharacterize the acoustic emission source during a measurement timeperiod, the spectral data or the time-averaged data including at leastone of a voltage amplitude, an energy value, or a frequency value, andfurther including generating an alert in response to the at least one ofthe voltage amplitude, the energy value, or the frequency valuesatisfying a threshold.
 11. The method of claim 8, further including:selecting a measurement bandwidth of the pre-amplified acoustic emissionsignal; combining (1) the chirp signal at a first instantaneousfrequency and (2) the pre-amplified acoustic emission signalcorresponding to the measurement bandwidth to generate the sidebandacoustic emission signal, the sideband acoustic emission signal shiftedaway from the measurement bandwidth based on the first instantaneousfrequency; and sampling the spectral data at the intermediate centerfrequency, the intermediate center frequency based on the firstinstantaneous frequency and the measurement bandwidth.
 12. The method ofclaim 8, further including adjusting a parameter of at least one of thepre-amplifier or a demodulator by at least one of modifying a gain of anamplifier, a bandwidth of a filter, a start frequency value of a chirpgenerator, an end frequency value of the chirp generator, a sweep timevalue of the chirp generator, or a communication parameter of atransmitter.
 13. The method of claim 8, further including: obtaining afirst value for a parameter from the data acquisition system; comparingthe first value to a second value for the parameter stored in a databaseincluded in the acoustic emission sensor; and replacing the second valuewith the first value in the database when the first and the secondvalues are different.
 14. The method of claim 8, further includingdisplaying the demodulated acoustic emission data on a presentationdevice included in the acoustic emission sensor.
 15. A non-transitorycomputer readable storage medium comprising instructions which, whenexecuted, cause a machine to at least: condition an acoustic emissionsignal based on an acoustic emission source with a pre-amplifierintegrated into an acoustic emission sensor to generate a pre-amplifiedacoustic emission signal; generate a chirp signal based on at least oneof a start frequency, an end frequency, or a sweep time; combine thepre-amplified acoustic emission signal with the chirp signal to generatea sideband acoustic emission signal; sample spectral data of thesideband acoustic emission signal at an intermediate center frequency inan intermediate frequency bandwidth; generate demodulated acousticemission data based on mapping the sampled spectral data to ameasurement center frequency to generate a low-resolution andhigh-bandwidth spectrum, the measurement center frequency different fromthe intermediate center frequency; and transmit the demodulated acousticemission data to a data acquisition system.
 16. The non-transitorycomputer readable storage medium of claim 15, wherein conditioning theacoustic emission signal includes at least one of strengthening theacoustic emission signal with an amplifier or removing frequencyinformation not within a frequency bandwidth with a filter.
 17. Thenon-transitory computer readable storage medium of claim 15, wherein thedemodulated acoustic emission data includes at least one of the spectraldata or time-averaged data to characterize the acoustic emission sourceduring a measurement time period, the spectral data or the time-averageddata including at least one of a voltage amplitude, an energy value, ora frequency value, and the instructions, when executed, cause themachine to at least generate an alert in response to the at least one ofthe voltage amplitude, the energy value, or the frequency valuesatisfying a threshold.
 18. The non-transitory computer readable storagemedium of claim 15, wherein the instructions, when executed, cause themachine to at least: select a measurement bandwidth of the pre-amplifiedacoustic emission signal; combine (1) the chirp signal at a firstinstantaneous frequency and (2) the pre-amplified acoustic emissionsignal corresponding to the measurement bandwidth to generate thesideband acoustic emission signal, the sideband acoustic emission signalshifted away from the measurement bandwidth based on the firstinstantaneous frequency; and sample the spectral data at theintermediate center frequency, the intermediate center frequency basedon the first instantaneous frequency and the measurement bandwidth. 19.The non-transitory computer readable storage medium of claim 15, whereinthe instructions, when executed, cause the machine to at least adjust aparameter of at least one of the pre-amplifier or a demodulator by atleast one of modifying a gain of an amplifier, a bandwidth of a filter,a start frequency value of a chirp generator, an end frequency value ofthe chirp generator, a sweep time value of the chirp generator, or acommunication parameter of a transmitter.
 20. The non-transitorycomputer readable storage medium of claim 15, wherein the instructions,when executed, cause the machine to at least: obtain a first value for aparameter from the data acquisition system; compare the first value to asecond value for the parameter stored in a database included in theacoustic emission sensor; and replace the second value with the firstvalue in the database when the first and the second values aredifferent.
 21. The non-transitory computer readable storage medium ofclaim 15, wherein the instructions, when executed, cause the machine toat least display the demodulated acoustic emission data on apresentation device included in the acoustic emission sensor.